1. Field of the Invention
The present invention relates to a charging member and to a process cartridge and an electrophotographic image-forming apparatus (hereinafter may be referred to as “electrophotographic apparatus”) including the charging member.
2. Description of the Related Art
An electrophotographic apparatus employing an electrographic system is mainly composed of an electrophotographic photoreceptor (hereinafter may be simply referred to as “photoreceptor”), a charging device, an exposure device, a developing device, a transfer device, and a fixing device. The charging device can be, for example, a roller-shaped or blade-shaped member or corona wire. In particular, a roller-shaped charging member (hereinafter may be simply referred to as “charging roller”) can be used. The charging device is disposed in contact with or in proximity to the surface of the photoreceptor and charges the surface of the photoreceptor by application of a voltage (a voltage of only a DC voltage or a voltage of superimposing an AC voltage on a DC voltage).
Japanese Patent Laid-Open No. 2008-276026 discloses a charging roller having protrusions due to conductive resin particles.
In the charging roller according to Japanese Patent Laid-Open No. 2008-276026, abutting of the charging roller against the photoreceptor concentrates the pressure on the protrusions due to the resin particles on the surface of the charging roller, resulting in uneven abrasion of the surface of the photoreceptor in use for a long time.
Regarding this problem, Japanese Patent Laid-Open No. 2011-237470 discloses a roller member that has an electro-conductive resin layer containing bowl-shaped resin particles each having an opening and has a surface having an uneven surface profile due to the opening portions and edge portions of the bowl-shaped resin particles. Japanese Patent Laid-Open No. 2011-237470 describes that in the roller member according to this invention, the edge portions of the bowl-shaped resin particles are elastically deformed in abutting against the photoreceptor to mitigate the abutting pressure and can prevent uneven abrasion of the photoreceptor even in use for a long time.
In addition, the literature “Optimal Design Method for Multi Dynamic Absorber, Transactions of the Japan Society of Mechanical Engineers. C 62(601) 1996/09” describes a method for designing a multi dynamic absorber.
The present invention is directed to providing a charging member that can sufficiently prevent occurrence of a banding image. The present invention is also directed to providing a process cartridge and an electrophotographic apparatus contributing to formation of a high-quality electrophotographic image.